Hydraulic latches



Dec. 18, 1956 D. e. LOOMIS 2,774,335

HYDRAULIC LATCHES Filed 001:. 4, 1955 2 Sheets-Sheet 1 INVENTOR. David G.Loomis BY- 4 I Dec. 18, 1956 D. G. LOOMIS 2,774,

HYDRAULIC LATCHEIS Filed Oct. 4, 1955 2 Sheets-Sheet 2 FIGS.

I H65. 70 I 1 f QDiavid U ited States P w HYDRAULIC LATCHES David G. Loomis, Newark, N. J.

Application October 4, 1955, Serial No. 538,374

7 Claims. (Cl. 12140) This invention relates to latches for hydraulic piston rods, and has for one of its objects the provision of a hydraulically-operated latch which will engage the piston rod when the same is in a retracted position and hold the same against extending movement such as might occur because of leakage into the cylinder.

The invention is particularly adapted for use in connection with hydraulic means, such as is employed in systems used on dumping scows wherein the doors of hoppers employed on such scows are hydraulically operated and wherein the possibility of any of the doors being accidentally opened due to leakage of hydraulic fluid into the actuating cylinders, must be avoided.

The improved latch construction is such as to be positive in operation and to lock the doors closed until the hydraulic cylinders are placed in readiness to operate in a manner to open the doors, and the latch being released to permit such operation.

It is another object of the invention to provide a latch in which the operating parts are available for inspection; in which no bending strain is imposed on the piston rod and which can be readily unlatched by hydraulic operation when the piston rod is under full load.

More particularly, the invention contemplates the pro vision of a toggle mechanism carrying a latch pawl that engages with a recess provided on a latch bar carried by the hydraulic piston rod, and in the provision of a hydraulic ram arranged to swing the toggle mechanism and the latch pawl carried by it in a manner to initiate a latchfreeing movement to thereby allow the piston rod to become effective to free the latch pawl from its engagement with the latch bar, and thus allow the latch to be moved to its open position.

With these, and other objects to be hereinafter set forth in view, I have devised the arrangement of parts to be described and more particularly pointed out in the claims appended hereto.

In the accompanying drawings, wherein an illustrative embodiment of the invention is disclosed,

Fig. 1 is a side elevational view of a hydraulic latch constructed in accordance with the invention;

Fig. 2 is a top plan view of the same;

Fig. 3 is a detail view, showing the latch in its open or unlocked position;

Fig. 4 is an end view of the latch, looking from the right of Fig. 1, and with the latch-operating hydraulic cylinder omitted;

Fig. 5 is a view looking at the under side of the latch, and

Fig. 6 is a sectional view, taken substantially on the line 6-6 of Fig. 5, looking in the direction of the arrows.

Referring to the drawings, 1 indicates a hydraulic cylinder in which a piston of known construction is operative in conventional manner, and to which a piston rod 2 is attached. The piston rod 2 is provided at the end 3 with the clevis 4 by which it may be attached to the mechanism that is intended to be operated by movements of the piston rod. The cylinder end cap is shown at 20 and pivotally attached at 8 to said end cap are two long link bars indicated respectively at 6 and 7, so that the cap is disposed between these bars. Adjacent to the opposite end of the link bars, and pivotally mounted between the same at 9 is a latch pawl 10 which has a rounded nose portion 21 adapted, when the latch is in its closed position, as shown in Figs. 1 and 2, to engage with a complementary groove or recess 22 formed in the latch bar 5 secured on, or formed as a part of, the piston rod 2 and thus being reciprocable with the piston rod.

At 15 is shown a latch-operating hydraulic cylinder ram which is disposed between and is carried by the link bars 6 and 7. Screws 16 and 17a attach the cylinder 15 to the link bars 6 and 7. The piston 17 of the hydraulic cylinder or ram 15 is disposed above the latch pawl 10 in such a manner that it is normally located over the latch pawl and is operative against a boss 23 formed on the latch pawl. I

In Figs. 1 and 2, the latch pawl is shown in its locked position, wherein it will be observed that the nose portion 21 of the latch pawl 10 is disposed in the groove 23 of the member 5 and behind the nub 25 thereon, so that any extending movement of the piston rod 2 toward the right will be thereby prevented. When hydraulic pressure is applied to the cylinder 15, the piston 17 thereof, operating against the boss 23 on the latch pawl 10, will force cylinder 15 upwardly. The cylinder 15 in such upward movement, carries the link bars 6 and 7 with it, swinging the bars 6 and 7 about their pivotal points 8. This causes a rotative movement of the latch pawl 10 in the groove 22 and only a short stroke of the piston 17 against the latch pawl is required to move the pawl to a position where movement of the piston rod 2 toward the right under pressure within cylinder 1 will swing the latch on its pivot 9 to free position. As the piston rod, with the latch bar 5 carried by it, continues to move to the right, it continues the swing of the latch bar in a counterclockwise direction until the movement of the same is halted by contact with pins 14 formed on rest plates 12 and 13 secured at opposite sides of the cylinder 1. These pins 14 halt the swinging movement of the latch pawl in a counter-clockwise direction and bring it to rest upon the elevated end portions 24 of the rest plates 12 and 13. The parts 24 of the rest plates 12 and 13 keep the latch pawl raised clear of the parts of the extended piston rod and insure proper engagement of the latch pawl with the nub 25 of the latch bar during return of the same'to latched position. Provision can be made, if necessary, to keep the latch bar 3 from rotative movement to insure proper engagement of the latch.

From the foregoing, it will be apparent that a latch is provided which can be readily unlatched by operation of the cylinder 15 when the piston rod is under full load; which does not impose bending loads on the piston rod, and due to the toggle linkage the ease of release of the latch may be readily made adjustable. Since the several parts of the latch are not enclosed, the same are readily available for inspection.

Having described a single embodiment of the invention, it is obvious that the same is not to be restricted thereto, but is broad enough to cover all structures coming within the scope of the annexed claims.

What I claim is:

l. A hydraulic latch of the character described comprising, a piston rod provided with a latch bar having a recess, a cylinder out of which the piston rod is extended, a pair of parallel links pivotally mounted on the cylinder, a hydraulic ram carried by the links, said ram having a cylinder and a piston, a pivoted latch pawl carried by the links and having a part for latching engagement with the recess to hold the piston rod against extension out of the cylinder, the piston of the ram being operative against Patented Dec. 18, 1956 the latch pawl to cause the cylinder of the ram to be moved to pivot the links and the latch to an extent to cause disengagement of the latch pawl from the recess under axial movement of the piston rod.v

2. A: hydraulic latch having a hydraulic'cylinder, a

piston rod for-movement out ofi the cylinder, a pivoted latch support, a hydraulic ram-carried thereby, said ram including a cylinder: anda piston, a latch pawl pivotally carried by the latch support, .a recess in the :piston rod -for engagement-by the latchpawl to thereby prevent axial movement in one direction of the. piston rod, the ram' being operative when the piston is extended against the pawl to cause the cylinder of the ram to be moved to' thereby'pivotally' move the pawl andits support in a manner to enableaxialmovement of the piston rod to 'free the latch from its engagement with the recess.

. 3. A hydraulic latch having a cylinder, a piston rod extending out of the same a latch bar carried'by the pistonrod; and formed with a latch-engaging groove, a

pair of spaced-apart, parallel link bars pivoted at one end cylinder of said ram to be moved away from the latch to thereby cause pivotal movementof the link'bars and to swing the latch on its pivot to a position wherein vaxial 'movement'of the piston rod will ,free the latch from its engagement with the recess and allow extending movement of the piston rod out of its cylinder.

4. A hydraulic latch of the character described, comprising a piston rod provided with a latch bar having a recess, a cylinder out of which the piston rod is extended,

a pair of pivotally-mounted, parallel links, a hydraulic ram having a cylinder mounted upon and carried between the links, a pivoted latch pawl pivoted between the links and having a part for latchingengagement with the recess to hold the piston rod against extension out-of-the cylinder, the ram having a piston operative against the latch pawl to cause the cylinder of the ram to be moved in a manner to pivot the links and 'the latch to an extent to cause disengagement of' the latch pawl from the'recess under axial movement of the piston rod, and means upon which the latch pawl is supported in disengaged position after its disengagement from the recess.

5. A hydraulic latch having a cylinder, a piston rod for movement out of the cylinder, a pivotedlatch support composed of a pair of parallel bars, a hydraulic ram having a cylinder bodily carried between said bars, a latch pawl pivotally carried between the bars, a recess s in the piston rod for engagement by the latch pawl to thereby prevent axial movement in one direction of'the piston rod, the ram havinga piston operative when extended against the pawl to pivotally move the same and also pivotally move the bars in a manner to enable axial movement of the piston rod to free the latch from its engagement with the recess.

6. A hydraulic latch h'aving a cylinder, a piston rod extending out of'the same, a latchbarcarried by the piston rod and formed with a latch-engaging groove, a pair of spaced-apart, parallel linkibars pivoted at one end on the cylinder a latch pivotally: mounted between-the link bars and adapted to engage with the groove, a hydraulic ram having a cylinder supported by and inovable with the link bars, said ram having a piston operative against the latch in a manner to cause pivotal movement of the link bars and to swingthe latch on its pivot to a position wherein axial movement of the piston rod will freethe latch fromits engagement with the recess and allow extendingmovement of the piston rod out of the cylinder, means. for supporting the latch in disengaged position after its disengagement from the groove, and stop'means' for limiting the pivotal movernent of the latch toward disengaged position. a

. 7. A hydraulic latch having a cylinder, a piston rod extending out of the same and provided with a latch engaging groove, a pair of spaced-apart parallel links between which the cylinder is located, said links being pivoted at one end to the cylinder, a latch pivotally." mounted between the links adjacent to the opposite end of said links, said latch being adapted for engagement with the groove, a hydraulic rarnhaving a cylinder fixedly mounted between the links adjacent to thepivotal'point.

of the latch, said cylinder being bodily movable with the links, the ram having a piston. with an end unconnected to but operative against the latch in a-mannerfto. cause pivotal movement of the links and swing the latch on its pivot to a position wherein axial movement of thepiston rod. will free the latch from its engagement with the groove and allow extending movement of the piston rod out of the cylinder, means located on the links for limiting pivotal movement of the latch in a direction toward disengaged position, and means disposed along opposite sides of the piston rod and situated between the links for supporting the latch indisengaged position after it has been disengaged from the groove.

2,515,237 Audermar s July-l8, 1 950 

